Method for positioning and/or guiding at least one arbitrary process head for the metallization of thin substrates at a defined distance above the substrate surface

ABSTRACT

A method for positioning or guiding at least one arbitrary print head or a printing unit having at least one pressure nozzle for the imprinting of thin substrates such as wafers at a defined distance above the surface of the substrate, which is to be provided on a support like a paddle or printing table. Distance sensors continuously acquired distance measurements to the surface of the substrate which is to be imprinted. An adjustment of the print head up to 6 degrees of freedom is ensured by actuators in such a manner that the section of the opening of the pressure nozzle of the print head can be adjusted so as to be coplanar to the section of the surface of the substrate which is to be imprinted. The print head is thus maintained or readjusted so as to adjust the section of the opening of the pressure nozzle of the print head to the surface of the substrate which is to be positioned on the support table so as to be coplanar and so as to maintain the coplanar position during the printing process.

FIELD AND BACKGROUND OF THE INVENTION

The invention relates to a method for positioning and/or guiding atleast one arbitrary process head (print head) or a printing unitcomprising at least one pressure nozzle for the metallization(imprinting) of thin substrates such as wafers at a defined distanceabove the surface of the substrate (wafer), which is to be provided on asupport (paddle; printing table). The invention also relates to adevice, comprising at least one print head for carrying out such amethod.

A screen printing machine for the solar cell production comprising aprinting unit, which can be moved up and down, and a printing table, viawhich a conveyor belt can be moved, wherein provision is made for apositioning device, which positions the solar cells on the conveyor beltso as to be accurately aligned to the printing unit, is known from DE 102006 558 A1. An adjusting device for the printing unit is not requiredhere.

In a screen printing method known from DE 692 30 099 T2, a substrate,which is to be imprinted, is fixed on a printing table, wherein thesubstrate and the screen, which is used, are provided with referencemarks. The position of the reference marks of the substrate applied onthe printing table is optically captured and stored by means of anobservation unit, which is positioned above the printing table. Inresponse to the positioning of the screen above the substrate, which isto be imprinted, the position of the reference marks of the screen andthe relative position of the screen to the substrate on the printingtable is determined thereby and the reference marks on the substrate andon the screen are aligned by means of a corresponding correction of theposition of the screen.

SUMMARY OF THE INVENTION

The invention is based on the object of providing a method and a deviceof the afore-mentioned type in such a manner that the positioning and/orguiding of at least one print head or of a printing unit comprising atleast one pressure nozzle for the metallization (imprinting) of thinsubstrates such as wafers at a defined distance above the substratesurface (wafer surface) is to be carried out effectively and accuratelyin such a manner that the section of the opening of the pressure nozzleof the print head is to be adjusted so as to be coplanar to the surfaceof the substrate (wafer), which is to be positioned on the supporttable, and so that the coplanar adjustment is to be maintained duringthe printing process.

According to the invention, this object is solved in that the section ofthe opening of the pressure nozzle of the print head is adjusted so asto be coplanar to the surface of the substrate (wafer), which is to bepositioned on the support table, and in that the coplanar adjustment ismaintained during the printing process in that

-   -   upper and lower distance sensors, respectively, are initially        positioned at the print head and at the support (paddle;        printing table) for the substrate (wafer) so as to correspond to        one another and so as to be calibrated according to a        calibrating routine, according to which the distance between the        upper and lower distance sensors, which are assigned to one        another, is determined by means of a standard body,

the incline of the surface of the support (paddle; printing table) forthe substrate (wafer) and, at the same time, the distance between areference section (reference plate) provided at the print head and thesection of the opening of the pressure nozzle are determined by means ofthe distance sensors,

-   -   the position of the pressure nozzle with reference to the        surface of the support (paddle; printing table) is subsequently        determined via the distance between the reference plate of the        print head and the section of the opening of the pressure nozzle        and the angle of inclination of the surface of the support        (paddle; printing table),    -   the respective thickness and thickness variations (wedge shape)        of the substrate (wafer), which is to be imprinted, are then        furthermore determined by means of a thickness and thickness        variation measuring device,    -   the section of the surface of the substrate (wafer), which is to        be imprinted, is determined in the space via the already        determined section of the surface of the support (paddle;        printing table) in the space and via the previously determined        geometry of the substrate (wafer) after a subsequent positioning        of the substrate (wafer) on the support (paddle; printing        table),    -   the print head is then set into rotation about its X and/or Y        axis by means of a process actuator until the section of the        opening of the pressure nozzle is adjusted so as to be coplanar        to the section of the surface of the substrate (wafer), which is        to be imprinted,    -   the two-dimensional arrangement of the substrate (wafer), which        is to be imprinted and which is positioned on the support        (paddle; printing table), is subsequently captured pictorially        by means of a camera,    -   the substrate (wafer) length, width and the angle γ of the        rotation of the substrate (wafer) position on the surface of the        support (paddle; printing table) are then determined with        reference to the Z axis of the print head by means of an image        evaluation,    -   the print head is subsequently rotated about its Z axis by means        of a process actuator according to the determined angle of        rotation γ,    -   the distance between the section of the opening of the pressure        nozzle and the surface of the substrate (wafer), which is to be        imprinted, is then continuously measured by means of the upper        distance sensors, which are provided at the print head,    -   the respective measuring data are subsequently input into a        process actuator for starting the forward movement of the print        head in the direction of the X axis (printing direction),    -   wherein the process actuator continuously advances the print        head in the direction of the X axis (printing direction) thereof        until the pressure nozzle reaches an initial printing position        via a feedback of the output of the process actuator to the        input thereof, said initial printing position being defined by        the previously determined position of the first flange of the        substrate (wafer), which is positioned on the surface of the        support (paddle; printing table)    -   and in which the operation of the pressure nozzle (printing        process) is started by means of the process actuator,    -   wherein the advance of the print head in the direction of the X        axis (printing direction) thereof and thus the operation of the        pressure nozzle is maintained via a feedback of the output of        the latter to the input of the process actuator until a final        printing position is reached, which is defined by the previously        determined position of the second flange of the substrate        (wafer), which is positioned on the support (paddle; printing        table), and in which the process actuator turns off the        operation of the pressure nozzle and    -   the process is subsequently ended immediately or only when the        determination of the section of the surface of a substrate        (wafer), which is to be imprinted subsequently, has been carried        out via the section of the surface of the support (paddle;        printing table), which is to be newly determined, and when the        evaluation of the thickness and thickness variation measurement        of the substrate (wafer), which is to be imprinted subsequently,        has been carried out.

The above-mentioned object of the invention is also solved by means of amethod of the afore-mentioned type, which is characterized by thefollowing method steps:

-   -   distance sensors, which are to be provided in each case at the        print head in printing direction upstream of the pressure        nozzle, are initially calibrated at a fixed distance to a        predetermined calibrating section and, at the same time, the        externally measured vertical distance between the section of the        distance sensors and the section of the opening of the pressure        nozzle is predetermined,    -   the position of the section of the opening of the pressure        nozzle in the space to the distance sensors at the print head is        subsequently determined via the measured vertical distance        between the section of the distance sensors and the section of        the opening of the pressure nozzle and via the fixed distance of        the distance sensors to the calibrating section,    -   the two-dimensional arrangement of the substrate (wafer), which        is to be imprinted and which is positioned on the support        (paddle; printing table), is subsequently captured pictorially        by means of a camera,    -   the substrate (wafer) length, width and the angle γ of the        rotation of the substrate (wafer) position on the surface of the        support (paddle; printing table) are subsequently determined        with reference to the Z axis of the print head by means of an        image evaluation,    -   the print head is subsequently moved and/or rotated on the        surface of the support (paddle; printing table) about its Z axis        about the angle γ in the direction of the Y axis until its        position corresponds with the captured position of the substrate        (wafer),    -   the continuous measurement of the distance between the distance        sensors, which advance ahead of the pressure nozzle, and the        surface of the substrate (wafer) is started and the obtained        measuring data are supplied to a process actuator for starting        the advance of the print head in the direction of the X axis        (printing direction),    -   wherein the print head is advanced in a controlled manner in the        direction of its X axis via a feedback of the output of the        process actuator to the input thereof until the distance sensor,        which advances ahead of the pressure nozzle, has captured the        first flange of the substrate (wafer), which is positioned on        the surface of the support (paddle; printing table),    -   the operation of the pressure nozzle (printing process) is then        started while continuing the advance of the print head in the        direction of the X axis (printing direction) and during a        continuous measurement of the distance between the distance        sensors advancing ahead of the pressure nozzle and the surface        of the substrate (wafer) and the obtained distance measuring        values are continuously compared with the predetermined        (defined) distance values by means of a signal comparator,        wherein, in response to an i.O. signal at the output of the        signal comparator, the advance of the print head in the        direction of the X axis is continuously continued via a feedback        to the input of the process actuator in the direction of the X        axis (printing direction) and    -   in response to a n.i.O. signal at the output of the signal        comparator, the print head is always adjusted in the direction        of the Z axis via a drive, which corresponds to the n.i.O.        signal and/or is inclined about the X axis and is further        advanced in the direction of the X axis (printing direction),        until the second flange of the substrate (wafer), which is        positioned on the support (paddle) and which is to be imprinted,        is captured by the distance sensors, which advance ahead of the        pressure nozzle, whereupon the operation of the pressure nozzle        of the print head (the printing process) is ended.

Preferably, the distance sensors capture the respective distance betweenthe print head and the surface of the substrate (wafer) by means oflaser triangulation, inferometrically, acoustically, chromaticallyconfocally, capacitively, inductively and/or on any other electric base.

The distance sensors can be queried analogously or at discrete points atcertain times (digitally) by means of the signal comparator.Inaccuracies in the mechanical attachment of the print head and/orpositional errors, thermal expansions and/or mechanical deformations ofthe wafer can also be advantageously determined by balancing themeasuring values captured by the distance sensors with predeterminedcorresponding setpoint values, which are stored in the signalcomparator, and which are compensated by a subsequent correspondingdrive of the process actuators at the respective print head.One-dimensional or two-dimensional process actuators are to be used forthe alignment of the process head (print head).

Preferably, the measurement of the distance between the print head andthe printing unit, respectively, and the surface of the substrate(wafer), are carried out by means of the distance sensors and thecontrol of the corresponding positioning of the print head takes placein an online manner. Preferably, the control of the positioning of theprint head is carried out by means of a robot, such as, e.g., a hexapod.

Advantageously, the calibration of the distance sensors and the controlof the process actuators is carried out according to a calibratingroutine, according to which provision is to be made for two upperdistance sensors at the respective print head in such a manner that theconnecting line thereof does not point in the direction of movement ofthe process (printing direction), that the two measuring points have twoparallel lines during the movement of the print head in response to themeasurement of the distance to the substrate surface and that two lowersensors are to be arranged next to the substrate (wafer) in such amanner that the print head is to be positioned above the lower sensorsin two positions A and B, wherein the distances between the two upperand the two lower distance sensors are measured in the first position Aand the distances between the two lower sensors and the pressure nozzlesof the print head are measured in the second position B.

Prior to the printing process, the substrate surface (wafer surface)must be known. Initially, a calibration thus takes place. For thispurpose, the four distances of the two upper sensors and the distancesof the print head to the two lower sensors are measured for this purposein position A and B of the print head. The differences result in aheight offset of the print head when a substrate (wafer) or a worknestsurface is measured with the supper sensors. Due to the fact that eachwafer encompasses an individual thickness and thickness variation (wedgeshape), these values are determined by each wafer ahead of time by meansof a suitable measuring device.

At the onset of the method, which is carried out according to theabove-mentioned calibrating routine, the calibration of the distancesensors is initially carried out at a fixed distance to the calibratingsection. At the same time, the vertical distance between a sensor andthe assigned pressure nozzle of the print head is measured externally.The respective measuring values from the calibration and from theexternal measurement of the vertical distance between distance sensorand pressure nozzle of the print head are supplied to an evaluationunit, which determines the position of the pressure nozzle of the printhead to the distance sensors, whereby the calibrating process is ended.

Preferably, the print head is moved in the direction of the printingmovement so as to be mounted at an alignment handling, which is formedfrom a plurality of metal plates, which are arranged parallel to oneanother and on top of one another, the uppermost metal plate of which isfixed so as to be immovable, wherein two adjacent metal plates are ineach case connected via guides, arbors and motors in terms of functionin such a manner that the respectively lower metal plate is to be movedwith at least one degree of freedom (displacements x, y, z and rotationsφ, θ) in addition to the degrees of freedom of the upper metal plate andthat the print head is thus to be positioned freely in the space in upto six degrees of freedom, wherein the direction of the printingmovement (x) is provided as the sole degree of freedom for the lowermostmetal plate.

Suitably, the individual thickness and thickness variations (wedgeshape) and/or the geometric surface structure of the thin substrate(wafer), which is to be imprinted, is initially determined by means of athickness and thickness variation measuring device and/or topographymeasuring system, whereupon the section of the substrate (wafer) surfaceis clearly determined by the calibration of the printing unit, which wascarried out previously, and by depositing the substrate (wafer), theprint head is oriented in all directions, except for the printingdirection x, in such a manner that the subsequent movements of the printhead in the printing direction x describe the section of the surface ofthe substrate (wafer) at a defined printing distance, wherein the printhead is first lifted from the substrate (wafer), is aligned and is movedinto the initial x position and is again moved into the requireddistance to the surface of the substrate (wafer) prior to the printingmovement.

The object of the invention is also solved by means of a devicecomprising at least one print head being characterized by an alignmenthandling, which mounts the print head in a movable manner and which isformed from a plurality of metal plates, which are mounted parallel ontop of one another, the uppermost metal plate of which is fixed so as tobe immovable, wherein the respectively lower metal plate is to be movedwith one or a plurality of degrees of freedom (displacements x, y, z androtations φ, θ) in addition to the degrees of freedom of the upper metalplate by means of guides, arbors and motors, which are provided in eachcase between two adjacent metal plates and the print head is thus to bepositioned freely in the space in up to six degrees of freedom and thedirection of the printing movement (x) is included in the lowermostmetal plate as the sole degree of freedom.

The method according to the invention and the device according to theinvention for carrying out said method enable a reliable and continuouscontrol and regulation of the positioning and/or guide of at least oneprocess head (print head and/or of a printing unit for the metallization(imprinting) of substrates such as wafers at a defined distance abovethe surface of the substrate (wafer) in a time-saving manner, whereinthe distance of the process head (print head) to the substrate surface(wafer surface) is determined during the printing by means of the upperdistance sensors. If a parameter changes during a printing series, thedetermination of this change and a corresponding adaptation of thealignment coordinates of the process head (print head) are givenimmediately.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be defined by means of the drawings.

FIGS. 1 a and 1 b show flow charts of the consecutive method steps of afirst embodiment of the method,

FIGS. 2 a and 2 b show flow charts of the consecutive method steps of asecond embodiment of the method,

FIG. 3 shows a front view (section Z-Y) of a schematically illustratedprint head for use in a first embodiment of the method,

FIGS. 4 a to 4 c show schematic illustrations in the Z-X section of theprint head used in the first embodiment of the method in consecutivestages of its movement in printing direction D,

FIG. 5 shows a schematic illustration of the print head, which is to beused in the first embodiment of the method comprising a predeterminedreference plate for determining the distance between the section of thedistance sensors at the print head and the section of the opening of thepressure nozzle of the print head,

FIG. 6 shows a top view of a schematic illustration of the position of awedge-shaped wafer, which is positioned on the surface of a support, andwhich is to be captured pictorially,

FIG. 7 shows a front view corresponding to that of FIG. 3 in the Z-Ysection of a schematically illustrated print head, which, however, isprovided for the use in the second embodiment of the method,

FIGS. 8 a to 8 c show schematic illustrations corresponding to those inFIGS. 3 a to 3 c in the Z-Y section, wherein the print head according toFIG. 7, which is used in the second embodiment of the method, isillustrated in consecutive stages of its movement in printing direction(arrow D),

FIG. 9 shows a schematic perspective illustration of a robot in the formof a hexapod comprising a print head mounted thereon and

FIG. 10 shows a schematic perspective view of an alignment handling,which consists of a plurality of parallel metal plates, which arearranged on top of one another, wherein a print head is mounted on thelowermost metal plate.

DETAILED DESCRIPTION

A first embodiment of the method for positioning and/or guiding at leastone arbitrary process head (print head) or a printing unit comprising atleast one pressure nozzle for the metallization (imprinting) of thinsubstrates such as wafers at a defined distance above the surface of thesubstrate (wafer), which is to be provided on a support (paddle;printing table), is now described with reference to FIGS. 1 a, 1 b, 3, 4a, 4 b, 4 c, 7 and 8.

FIG. 3 shows, schematically in a side view, a print head 1 in thesection Z; Y, which is mounted on an alignment handling, which is notshown in FIG. 3, and which can be moved together with said alignmenthandling by means of a robot comprising three degrees of translationalfreedom and three degrees of rotational freedom. The print head 1encompasses a pressure nozzle 2 at its lower surface 3, which is to bealigned to a wafer 4 having a typically wedge-shaped form and said waferis to be positioned on a wafer holder located on a table top 5 or on asupport 6 at a distance to the section of the opening of the pressurenozzle 2. Provision is made on the lower surface 3 of the print head 1and oppositely at the wafer holder 6 for upper and lower distancesensors 7 and 8, respectively, so as to be assigned to one another,wherein the upper distance sensors 7 are positioned in printingdirection (arrow D) of the pressure nozzle 2 arranged downstream at theprint head 1, as can be seen from FIGS. 4 a to 4 c, which show the printhead 1 in the Z-X section in three consecutive stages of the movement inprinting direction (arrow D), i.e., when reaching a first flange K₁ ofthe wafer 4 (FIG. 4 a), which is positioned on the surface 9 of thesupport 6, in printing position above the surface 10 of the wafer 4(FIG. 4 b), which is positioned on the surface 9 of the support 6, andafter the surface 10 of the wafer 4 (FIG. 4 c), which is positioned onthe surface 9 of the support 6, has been imprinted.

As can be seen from the flow charts shown in FIGS. 1 a and 1 b, thefollowing method steps A₁-A₁₈ are carried out consecutively so as toadjust the section of the opening of the pressure nozzle 2 of the printhead 1 to the surface 10 of the wafer 4, which is positioned on thesurface 9 of the support 6, so as to be coplanar and so as to maintainthe coplanar position during the printing process:

-   A₁ and A₂: The upper and lower distance sensors 7, which are to be    positioned in pairs on the print head 1 and on the support 6 for the    wafers 2, are initially calibrated according to a calibrating    routine, according to which the distance between the upper and lower    distance sensors 7 and 8, respectively, which are arranged in pairs,    is determined in a standard manner by means of a standard body.-   A₃: The inclination of the surface 9 of the support 6 for the wafer    2 is then determined by means of the distance sensors 7 and 8,    respectively, and-   A₄: as can be seen from FIG. 5, the distance d between a reference    plate 11 provided at the print head 1 and the section of the opening    of the pressure nozzle 2 is determined at the same time, i.e., via    the distance a between the upper and lower distance sensors 7 and 8,    respectively, the distance b between the upper distance sensors and    the surface 9 of the support 6, the distance c between the section    of the opening of the pressure nozzle 2 and the surface 9 of the    support 6 and via the distance e between the reference plate 11 at    the print head 1 and the lower distance sensors 8.-   A₅: The position of the pressure nozzle 2 with reference to the    surface 9 of the support 6 is determined subsequently via the    distance between the reference plate 11 at the print head 1 and the    section of the opening of the pressure nozzle 2 and via the angle of    inclination of the surface 9 of the support 6 for the wafer 4.-   A₆: The thickness and the thickness variations (wedge shape) of the    wafer 2, which is to be imprinted, are then determined by means of a    thickness and thickness variation measuring device.-   A_(7a) and A_(7b): After positioning the wafer 4 on the surface 9 of    the support 6, the section of the surface 10 of the wafer 4, which    is to be imprinted, is then determined in the space via the already    determined section of the surface 9 of the support 6 in the space    and via the previously determined geometry of the wafer 4.-   A₈: The print head 1 is subsequently rotated about is X and/or Y    axis by means of a process actuator 12 until the section of the    opening of the pressure nozzle 2 is adjusted so as to be coplanar to    the section of the surface 10 of the wafer 4, which is to be    imprinted.-   A₉: The two-dimensional arrangement of the wafer 4 illustrated in    FIG. 6, which is positioned on the surface 9 of the support 6 and    which is to be imprinted, is subsequently captured pictorially by    means of a camera.-   A₁₀: The wafer length, width and the angle γ of the rotation of the    wafer position on the surface 9 of the support 6 with reference to    the Z axis of the print head 1 are then determined by means of an    image evaluation.-   A₁₁: The print head 1 is rotated subsequently about its Z axis    according to the determined angle of rotation γ by means of a    process actuator.-   A₁₂: The distance between the section of the opening of the pressure    nozzle 2 and the surface 10 of the wafer 4, which is to be    imprinted, is then continuously measured by means of the upper    distance sensors 7 provided at the print head 1.-   A₁₃: The respective measuring data are subsequently input into the    process actuator for starting the forward movement of the print head    1 in the direction of the X axis (printing direction).-   A₁₄: The print head 1 is continuously advanced via a feedback from    the output of the process actuator to the input thereof in the    direction of the X axis (printing direction) until the pressure    nozzle 2 has reached an initial printing position 14 (FIG. 3A),    which is defined by the previously determined position of the first    flange K₁ of the wafer 4, which is positioned on the surface 9 of    the support 6.-   A₁₅: The operation of the pressure nozzle 2 is started by means of    the process actuator in the initial printing position.-   A₁₆: The advance of the print head 1 in the direction of the X axis    (printing direction) and thus the operation of the pressure nozzle 2    is maintained via a feedback of the output of the process actuator    to the input thereof until a final printing position is reached,    which is defined by the previously determined position of the second    flange K₂ of the wafer 4, which is positioned on the surface 9 of    the support 6, in which the process actuator turns off the operation    of the pressure nozzle 2.-   A₁₇: The process is subsequently ended immediately-   A₁₈: or only when, after the pressure nozzle 2 was turned off and    thus after the surface 12 of the wafer 4 was imprinted, the    determination of the section of the surface of a wafer, which is to    be imprinted subsequently, has been carried out via the section of    the surface 9 of the support 10, which is to be determined again,    and when the evaluation of the thickness and thickness variation    measurement of the wafer, which is to be imprinted subsequently, has    been carried out.

FIG. 7 shows a front view of the print head 1 in the Z-Y section, whichcorresponds to that of FIG. 3, where the second embodiment of the methodis used. As can be seen in FIGS. 8 a to 8 c, which show the print head 1in the Z-X section in three consecutive stages of the movement inprinting direction (arrow D) in accordance with FIGS. 4 a to 4 c, thedistance sensors 15 provided here at the print head are positioned inprinting direction (arrow D) upstream of the pressure nozzle 2.

As is shown in the flow charts shown in FIGS. 2 a and 2 b, the followingmethod steps B₁ to B₁₆ are carried out consecutively so as to adjust thesection of the opening of the pressure nozzle 2 of the print head 1 tothe surface 10 of the wafer 4, which is positioned on the surface 9 ofthe support 6, so as to be coplanar and so as to maintain the coplanarposition during the guiding of the print head across the surface 10 ofthe wafer 4, which is to be imprinted, and/or so as to again adjust saidsection in response to deviations:

-   B₁: The distance sensors 14, which are to be provided in each case    at the print head 1 in printing direction (arrow D) upstream of the    pressure nozzle 2 are initially calibrated at a fixed distance to a    predetermined calibrating section;-   B₂: the predetermined vertical distance between the section of the    distance sensors 14 and the section of the opening of the pressure    nozzle 2 are introduced into the method at the same time.-   B₃: The section of the opening of the pressure nozzle 2 in the space    to the distance sensors 14 at the print head 1 is determined    subsequently via the measured vertical distance between the section    of the distance sensors 14 and the section of the opening of the    pressure nozzle 2 and via the fixed distance of the distance sensors    14 to the predetermined calibrating section.-   B₄: The two-dimensional arrangement of the wafer 4, which is to be    imprinted and which is positioned on the surface 9 of the support 6,    is then captured pictorially by means of a camera.-   B₅: The wafer length, width and the angle γ of the rotation of the    wafer position on the surface 9 of the support 6 are then determined    with reference to the Z axis of the print head 1 by means of an    image evaluation.-   B₆: The print head 1 is then moved in the direction of the Y axis    until its position corresponds with the captured position of the    wafer 4 on the surface 9 of the support 6 and is simultaneously    rotated about its Z axis about the angle γ.-   B₇: The continuous measurement of the distance between the distance    sensors 14 positioned in printing direction (arrow D) upstream of    the pressure nozzle 2 at the print head 1 and the surface 10 of the    wafer 4, which is to be imprinted, is subsequently initiated.-   B₈: The obtained measuring data are supplied to a process actuator    for starting the advance of the print head 1 in the direction of the    X axis (printing direction).-   B₉: The print head 1 is advanced via a feedback of the output of the    process actuator to the input thereof in the direction of the X axis    in a control manner until the distance sensors 14, which advance    ahead of the pressure nozzle, have captured the first flange K₁ of    the wafer 4, which is positioned on the surface 9 of the support 6,    at the print head 1.-   B₁₀: The advance of the print head 1 in the direction of the X axis    (printing direction) is continued at the same time and-   B₁₁: the operation of the pressure nozzle 2 is started,-   B₁₂: wherein the continuous measurement of the distance between the    distance sensors 15 at the print head 1, which advance ahead of the    pressure nozzle 2, and the surface 10 of the wafer, which is to be    imprinted, is continued.-   B₁₃: The obtained distance measuring values are continuously    compared with the predetermined (defined) distance values in a    signal comparator,    -   wherein, in response to an i.O. signal at the output of the        signal comparator, the advance of the print head 1 in the        direction of the X axis is continued in a continuously        controlled manner via a feedback of the output of the process        actuator to the input thereof.-   B₁₄: In response to a n.i.O. signal at the output of the signal    comparator, the print head is always adjusted via a drive in the    direction of the Z axis and/or is correspondingly inclined about the    X axis before the print head 1 is further advanced in the direction    of the X axis.-   B₁₅: The advance of the print head 1 in the direction of the X axis    is carried out continuously via a feedback to the input of the    process actuator, provided that the second flange K₂ of the wafer 4,    which is positioned on the surface 9 of the support 6, is not    captured by the distance sensors 14, which advance ahead of the    pressure nozzle 2 in printing direction (arrow D).-   B₁₆: The operation of the pressure nozzle 2 is turned off and the    printing process is thus ended when the second flange K₂ of the    imprinted wafer 4, which is positioned on the surface 9 of the    support 6, is captured by means of the distance sensors 14 at the    print head 1, which advance ahead of the pressure nozzle 2 in    printing direction (arrow D).

FIG. 9 shows, schematically, a robot 15 comprising a parallelkinematics, a so-called hexapod, for controlling the translatory andarbitrarily rotational movement of the print head 1. This robot 15 canposition the working surface 16, e.g., a small plate-like disk, in all 6degrees of freedom in that actuators 17, which are formed by electriccylinders, for example, are extended and retracted in a known manner. Toattain a large lift in X axis, the working surface 16 of the robot 15can be mounted on a linear axis 18, along which the robot 15 is to bemoved for imprinting the wafer 4 and for moving the pressure nozzle 2into a cleaning station. Position adjustments of the print head 1 bymeans of the robot 15 are then possible in the Y and in the Z axis aswell as in the 3 degrees of rotational freedom. The printing movement ofthe print head 1 is to be carried out in an extremely smooth manner bymeans of the linear axis 18.

FIG. 10 shows, schematically, an alignment handling 20 formed from aplurality of parallel metal plates 19, which are arranged on top of oneanother, on the lowermost metal plate 19 of which the print head 1 ismounted. The uppermost metal plate 19 is fixed so as to be immovable andtwo adjacent metal plates 19 are in each case connected via guides,arbors and motors in terms of function in such a manner that therespectively lower metal plate 19 is to be moved with at least onedegree of freedom (displacements in X, Y and Z axis and rotations φ, θ)in addition to the degrees of freedom of the upper metal plate 19. Theprint head 1 mounted on the alignment handling 20 is thus to bepositioned freely in the space in up to six degrees of freedom, whereinthe direction of the printing movement x (arrow D) is provided as thesole degree of freedom for the lowermost metal plate 19.

REFERENCE LIST

-   A₁ to A₁₇ method steps of the first embodiment of the method-   B₁ to B₁₈ method steps of the second embodiment of the method-   1 print head-   2 pressure nozzle-   3 lower surface of the print head-   4 substrate, wafer (wedge-shaped)-   5 table top-   6 support; wafer holder-   7 upper distance sensors at the print head in printing direction D    arranged downstream from the pressure nozzle-   8 lower distance sensors at the support-   9 surface of the support-   10 surface of the wafer, which is to be imprinted-   11 reference plate at the print head-   12 process actuator-   13 initial printing position-   14 distance sensors at the print head in printing direction D    upstream of the pressure nozzle-   15 robot; hexapod-   16 working surface of the robot; small plate-like disk-   17 actuators; electric cylinders-   18 linear axis for working surface 16-   19 metal plates-   20 alignment handling-   Arrow D printing direction-   γ angle of the rotation of the wafer, which is positioned on the    surface of the support, about the Z axis-   x,y,z translatory degrees of freedom, movement axes of the print    head-   φ, θ, γ rotational degrees of freedom-   K₁; K₂ flanges of the wafer, which is positioned on the surface of    the support

1) A method for positioning and/or guiding at least one arbitraryprocess head (print head) or a printing unit comprising at least onepressure nozzle for the metallization (imprinting) of thin substratessuch as wafers at a defined distance above the surface of the substrate(wafer), which is to be provided on a support (paddle; printing table),characterized in that the section of the opening of the pressure nozzleof the print head is adjusted so as to be coplanar to the surface of thesubstrate (wafer), which is to be positioned on the support table, andin that the coplanar adjustment is to be maintained during the printingprocess in that upper and lower distance sensors are initiallypositioned at the print head and at the support (paddle; printing table)for the substrate so as to correspond to one another and so as to becalibrated according to a calibrating routine, according to which thedistance between the upper and lower distance sensors, which areassigned to one another, is determined by means of a standard body, theincline of the surface of the support (paddle; printing table) for thesubstrate and, at the same time, the distance between a referencesection (reference plate) provided at the print head and the section ofthe opening of the pressure nozzle are determined by means of thedistance sensors, the position of the pressure nozzle with reference tothe surface of the support (paddle; printing table) is subsequentlydetermined via the distance between the reference plate of the printhead and the section of the opening of the pressure nozzle and via theangle of inclination of the surface of the support (paddle; printingtable), the respective thickness and thickness variations (wedge shape)of the substrate (wafer), which is to be imprinted, are then determinedby means of a thickness and thickness variation measuring device, thesection of the surface of the substrate (wafer), which is to beimprinted, is determined in the space via the already determined sectionof the support (paddle; printing table) in the space and via thepreviously determined geometry of the substrate (wafer) after asubsequent positioning of the substrate (wafer) on the support (paddle;printing table), the print head is then rotated about its X and/or Yaxis by means of a process actuator until the section of the opening ofthe pressure nozzle is adjusted so as to be coplanar to the section ofthe surface of the substrate (wafer), which is to be imprinted, thetwo-dimensional arrangement of the substrate (wafer), which is to beimprinted and which is positioned on the support (paddle; printingtable), is subsequently captured pictorially by means of a camera, thesubstrate (wafer) length, width and the angle γ of the rotation of thesubstrate (wafer) position on the surface of the support (paddle;printing table) are then determined with reference to the Z axis of theprint head by means of an image evaluation, the print head issubsequently rotated about its Z axis by means of a process actuatoraccording to the determined angle of rotation γ, the distance betweenthe section of the opening of the pressure nozzle and the surface of thesubstrate (wafer), which is to be imprinted, is then continuouslymeasured by means of the upper distance sensors, which are provided atthe print head, the respective measuring data are subsequently inputinto a process actuator for starting the forward movement of the printhead in the direction of the X axis (printing direction) thereof,wherein the print head is continuously advanced in the direction of theX axis (printing direction) until the pressure nozzle reaches an initialprinting position via a feedback from the output of the process actuatorto the input thereof, said initial printing position being defined bythe previously determined position of a first flange of the substrate(wafer), which is positioned on the surface of the support (paddle;printing table) and in which the operation of the pressure nozzle(printing process) is started by means of the process actuator, whereinthe advance of the print head in the direction of the X axis (printingdirection) and thus the operation of the pressure nozzle is continuedvia a feedback of the output of the latter to the input of the processactuator until a final printing position is reached, which is defined bythe previously determined position of a second flange of the substrate(wafer), which is positioned on the surface of the support (paddle;printing table) and in which final printing position the processactuator turns off the operation of the pressure nozzle and the processis subsequently ended immediately or only when, after the imprinting ofthe substrate (wafer) has been completed, the determination of thesection of the surface of a substrate (wafer), which is to be imprintedsubsequently, has been carried out via the section of the surface of thesupport (paddle; printing table), which is to be newly determined, andwhen the evaluation of the thickness and thickness variation measurementof the substrate (wafer), which is to be imprinted subsequently, hasbeen carried out. 2) The method according to claim 1, characterized inthat the distance sensors capture the respective distance, which is tobe measured, by means of laser triangulation, inferometrically,acoustically, chromatically confocally, capacitively, inductively and/oron any other electric base. 3) The method according to claim 1,characterized in that the distance sensors are queried analogously or atdiscrete points at certain times (digitally) by means of the signalcomparator. 4) The method according to claim 1, characterized in thatinaccuracies in the mechanical attachment of the print head and/orpositional errors, thermal expansions and/or mechanical deformations ofthe wafer can be determined by balancing the measuring values capturedby the distance sensors with predetermined corresponding setpointvalues, which are stored in the signal comparator, and which arecompensated by a subsequent corresponding drive of the process actuatorsat the respective print head. 5) The method according to claim 1,characterized in that one-dimensional or two-dimensional processactuators are used for the alignment of the process head (print head).6) The method according to claim 1, characterized in that themeasurement of the distance between the print head and the surface ofthe substrate take place by means of the distance sensors and thecontrol of the corresponding positions thereof takes place in an onlinemanner. 7) The method according to claim 1, characterized in that theadjustment movements of the print head are carried out by means of arobot, such as an hexapod. 8) The method according to claim 1,characterized in that the calibration of the distance sensors and thecontrol of the process actuators is carried out according to acalibrating routine, according to which provision is to be made for twoupper distance sensors at the respective print head in such a mannerthat the connecting line thereof does not point in the direction ofmovement of the process (printing direction), that the two measuringpoints describe two parallel lines during the movement of the print headin response to the measurement of the distance to the substrate surfaceand that two lower sensors are to be arranged next to the substrate(wafer) in such a manner that the print head is to be positioned abovethe lower sensors in two positions A and B, wherein the substratesurface, which is to be imprinted, is to be predetermined prior to theprinting process, the distances between the two upper and the two lowerdistance sensors are then measured in the first position and thedistances between the two lower sensors and the pressure nozzles of theprint heads are measured in the second position B and a height offset ofthe print head is obtained via the differences when the substratesurface is measured by means of the upper sensors. 9) The methodaccording to claim 1, characterized in that the print head is moved inthe direction of the printing movement so as to be mounted at analignment handling, which is formed from a plurality of metal plates,which are arranged parallel to one another and on top of one another,the uppermost metal plate of which is fixed so as to be immovable,wherein two adjacent metal plates are in each case connected via guides,arbors and motors in terms of function in such a manner that therespective lower metal plate is to be moved with at least one degree offreedom (displacements x, y, z and rotations φ, θ) in addition to thedegrees of freedom of the upper metal plate and the print head is thusto be positioned freely in the space in up to six degrees of freedom,wherein the direction of the printing movement (x) is provided as thesole degree of freedom for the lowermost metal plate (19). 10) Themethod according to claim 9, characterized in that the individualthickness and thickness variations (wedge shape) of the substrate(wafer), which is to be imprinted, are initially determined by means ofa thickness and thickness variation measuring device and/or a topographymeasuring system, whereupon the section of the substrate (wafer) surfaceis clearly determined by the calibration of the printing unit, which wascarried out previously, and by depositing the substrate (wafer), theprint head is oriented in all directions, except for the printingdirection x, in such a manner that the subsequent movements of the printhead in the printing direction x describe the section of the substrate(wafer) surface at a defined printing distance, wherein the print headis first lifted from the substrate (wafer), is aligned and is moved intothe initial x position and is again moved into the required distance tothe substrate (wafer) surface prior to the printing movement. 11) Adevice comprising at least one print head for carrying out the methodaccording to claim 1, characterized by an alignment handling (20), whichmounts the print head (1) so as to be movable and which is formed from aplurality of metal plates (19), which are arranged parallel to oneanother and on top of one another, the uppermost metal plate (19) ofwhich is fixed so as to be immovable, wherein the respective lower metalplate (19) is to be moved with at least one degree of freedom(displacements x, y, z and rotations φ, θ) in addition to the degrees offreedom of the upper metal plate (19) by means of guides, arbors andmotors, which are provided between two respective adjacent metal plates(19), and the print head (1) is thus to be positioned freely in thespace in up to six degrees of freedom and the direction of the printingmovement (x) is included as the sole degree of freedom in the lowermostmetal plate (19). 12) The method for positioning and/or guiding at leastone arbitrary process head (print head) or a printing unit comprising atleast one pressure nozzle for the metallization (imprinting) of thinsubstrates such as wafers at a defined distance above the surface of thesubstrate (wafer), which is to be provided on a support (paddle;printing table), characterized by the following method steps: distancesensors, which are to be provided in each case at the print head inprinting direction upstream of the pressure nozzle, are initiallycalibrated at a fixed distance to a predetermined calibrating sectionand the vertical distance between the section of the distance sensorsand the section of the opening of the pressure nozzle is predetermined,the position of the section of the opening of the pressure nozzle withreference to the distance sensors positioned at the print head aresubsequently determined via the predetermined vertical distance betweenthe section of the distance sensors and the section of the opening ofthe pressure nozzle and via the fixed distance of the distance sensorsto the calibrating section, the two-dimensional arrangement of thesubstrate (wafer), which is to be imprinted and which is positioned onthe support (paddle; printing table), is subsequently capturedpictorially by means of a camera, the substrate (wafer) length, widthand the angle γ of the rotation of the substrate (wafer) position on thesurface of the support (paddle; printing table) are subsequentlydetermined with reference to the Z axis of the print head by means of animage evaluation, the print head is subsequently moved and/or rotatedabout its Z axis about the angle γ in the direction of the Y axis untilits position corresponds with the captured position of the substrate(wafer) on the surface of the support (paddle; printing table), thecontinuous measurement of the distance between the distance sensors,which advance ahead of the pressure nozzle, and the surface of thesubstrate (wafer) is started subsequently, the obtained measuring dataare then input into a process actuator for starting the advance of theprint head in the direction of the X axis (printing direction), whereinthe print head is advanced in a controlled manner in the direction ofthe X axis via a feedback of the output of the process actuator to theinput thereof until the distance sensors, which advance ahead of thepressure nozzle, capture a first flange of the substrate (wafer), whichis positioned on the support (paddle; printing table), the operation ofthe pressure nozzle (printing process) is then started, the advance ofthe print head in the direction of the X axis (printing direction) iscontinued and, at the same time, the continuous measurement of thedistance between the distance sensors, which advance ahead of thepressure nozzle and the surface of the substrate (wafer) is started,wherein the obtained distance measuring values are continuously comparedwith the predetermined (defined) distance values by means of a signalcomparator, in response to an i.O. signal at the output of the signalcomparator, the advance of the print head in the direction of the X axis(printing direction) is continued via a corresponding feedback to theprocess actuator and in response to a n.i.O. signal at the output of thesignal comparator, the print head is initially adjusted in the directionof the Z axis via a drive, which corresponds to the n.i.O. signal,and/or is inclined about the X axis and is only then further advancedfor the advance in the direction of the X axis (printing direction) viaa feedback to the process actuator until a second flange of thesubstrate (wafer), which is positioned on the support (paddle) and whichis to be imprinted, is captured by the distance sensors, which advanceahead of the pressure nozzle, whereupon the operation of the pressurenozzle of the print head (the printing process) is ended. 13) The methodaccording to claim 12, characterized in that the distance sensorscapture the respective distance, which is to be measured, by means oflaser triangulation, inferometrically, acoustically, chromaticallyconfocally, capacitively, inductively and/or on any other electric base.14) The method according to claim 12, characterized in that the distancesensors are queried analogously or at discrete points at certain times(digitally) by means of the signal comparator. 15) The method accordingto claim 12, characterized in that inaccuracies in the mechanicalattachment of the print head and/or positional errors, thermalexpansions and/or mechanical deformations of the wafer can be determinedby balancing the measuring values captured by the distance sensors withpredetermined corresponding setpoint values, which are stored in thesignal comparator, and which are compensated by a subsequentcorresponding drive of the process actuators at the respective printhead. 16) The method according to claim 12, characterized in thatone-dimensional or two-dimensional process actuators are used for thealignment of the process head (print head). 17) The method according toclaim 12, characterized in that the measurement of the distance betweenthe print head and the surface of the substrate take place by means ofthe distance sensors and the control of the corresponding positionsthereof takes place in an online manner. 18) The method according toclaim 12, characterized in that the adjustment movements of the printhead are carried out by means of a robot, such as an hexapod. 19) Themethod according to claim 12, characterized in that the calibration ofthe distance sensors and the control of the process actuators is carriedout according to a calibrating routine, according to which provision isto be made for two upper distance sensors at the respective print headin such a manner that the connecting line thereof does not point in thedirection of movement of the process (printing direction), that the twomeasuring points describe two parallel lines during the movement of theprint head in response to the measurement of the distance to thesubstrate surface and that two lower sensors are to be arranged next tothe substrate (wafer) in such a manner that the print head is to bepositioned above the lower sensors in two positions A and B, wherein thesubstrate surface, which is to be imprinted, is to be predeterminedprior to the printing process, the distances between the two upper andthe two lower distance sensors are then measured in the first positionand the distances between the two lower sensors and the pressure nozzlesof the print heads are measured in the second position B and a heightoffset of the print head is obtained via the differences when thesubstrate surface is measured by means of the upper sensors. 20) Themethod according to claim 12, characterized in that the print head ismoved in the direction of the printing movement so as to be mounted atan alignment handling, which is formed from a plurality of metal plates,which are arranged parallel to one another and on top of one another,the uppermost metal plate of which is fixed so as to be immovable,wherein two adjacent metal plates are in each case connected via guides,arbors and motors in terms of function in such a manner that therespective lower metal plate is to be moved with at least one degree offreedom (displacements x, y, z and rotations φ, θ) in addition to thedegrees of freedom of the upper metal plate and the print head is thusto be positioned freely in the space in up to six degrees of freedom,wherein the direction of the printing movement (x) is provided as thesole degree of freedom for the lowermost metal plate (19). 21) Themethod according to claim 20, characterized in that the individualthickness and thickness variations (wedge shape) of the substrate(wafer), which is to be imprinted, are initially determined by means ofa thickness and thickness variation measuring device and/or a topographymeasuring system, whereupon the section of the substrate (wafer) surfaceis clearly determined by the calibration of the printing unit, which wascarried out previously, and by depositing the substrate (wafer), theprint head is oriented in all directions, except for the printingdirection x, in such a manner that the subsequent movements of the printhead in the printing direction x describe the section of the substrate(wafer) surface at a defined printing distance, wherein the print headis first lifted from the substrate (wafer), is aligned and is moved intothe initial x position and is again moved into the required distance tothe substrate (wafer) surface prior to the printing movement. 22) Adevice comprising at least one print head for carrying out the methodaccording to claim 12, characterized by an alignment handling (20),which mounts the print head (1) so as to be movable and which is formedfrom a plurality of metal plates (19), which are arranged parallel toone another and on top of one another, the uppermost metal plate (19) ofwhich is fixed so as to be immovable, wherein the respective lower metalplate (19) is to be moved with at least one degree of freedom(displacements x, y, z and rotations φ, θ) in addition to the degrees offreedom of the upper metal plate (19) by means of guides, arbors andmotors, which are provided between two respective adjacent metal plates(19), and the print head (1) is thus to be positioned freely in thespace in up to six degrees of freedom and the direction of the printingmovement (x) is included as the sole degree of freedom in the lowermostmetal plate (19).